The main objective of this research is to elucidate the inter-relationships between accumulated lead burden measured by K-X-Ray Fluorescence (K-XRF), blood lead levels, dietary calcium, and blood pressure. Previous studies have shown a positive cross-sectional association between blood lead at low levels experienced by the general population and blood pressure and a negative association between dietary calcium and blood pressure. There have been no studies that have assessed the possibility that accumulated lead burden is more closely associated than blood lead with blood pressure increases, and that lead may confound the relationship between dietary calcium and blood pressure; and no studies on the longitudinal relationship between blood lead levels and blood pressure at multiple points in time. The specific aims are focused on examining the above relationships in the Normative Aging Study (NAS), a group of men who have been followed longitudinally since 1962 and are expected to have accumulated lead burdens from low-level environmental exposures that are similar to those sustained by the general population. In preliminary studies we discuss data on blood lead levels, dietary calcium, and blood pressure in the NAS; a study validating the use of frozen red cells for lead analysis in the NAS; our state-of-the art K-XRF instrument and its precision, accuracy, and calibration; two population studies of K-XRF; and a study of the distribution of lead in cadaveric skeletons. In the research plan we propose to use our K-XRF instrument to measure lead burden in NAS subjects, thaw and analyze frozen red cell samples that are available on each NAS subject from multiple visits since the 1960s, and continue collection of fresh blood leads. This would add to the data already being collected, including dietary information using a semi-quantitative food frequency questionnaire, 24 hour urinary amines, blood pressures, and many other physical exam and laboratory parameters. Finally, we outline our strategy for analysis of the data including specific approaches for the blood lead-blood pressure data at multiple points in time.